Renewed clashes have killed over 50 anti-government protestors after two days of violence the AFP reports.
The US embassy in Sanaa has called for restraint and a peaceful transfer of power from President Saleh to his deputy.
"The United States regrets the deaths and injuries of many people during protest marches in Sanaa yesterday (Sunday). In this tense situation, we call upon all parties to exercise restraint," the statement said.
"The United States continues to support a peaceful and orderly transition in Yemen, one which addresses the Yemeni people's aspirations for peace and security.
"We remain hopeful that an agreement will be reached that leads to the signing of the GCC initiative within one week."
The latest violence comes as UN and GCC envoys arrived in Sanaa to push through an agreement for the transition of power from Saleh to his deputy.